The Discovery of Saturn

By Ping

K.L. Carver ThinkQuest Team 1998

One dark night in the year 1610, the Italian scientistGalileo pointed a

simple telescope toward the planet Saturn. It was the firsttime anyone

had ever seen Saturn through a telescope.

The telescope wasn't very good. The planet looked blurrythrough them,

but that didn't matter. Galileo had discovered a planet.The planet was

round and had two bumps on the sides. Galileo called thebumps "ears."

He didn't live long enough to find out what they reallywere. A Dutch

scientist named Christiaan Huygens answered that questionyears later.

In 1656, Huygens used a bigger and better telescope tolook at Saturn.

He decided that the "ears" were really a solidring surrounding the

planet.

Astronomers built still larger and better telescopes. Andthe view of

Saturn became clearer and clearer. In 1675 a French astronomernamed

Jean Domonique Cassini found a dark band running throughthe center of

the ring. The dark band was really a gap, dividing thering in two. It

was named the Cassini Division, after its discoverer.

Now Saturn was known to have two rings. And astronomersthought that

the rings weren't solid after all. Cassini also discoveredfour moons

orbiting Saturn.

And so it went. With each improved telescope, astronomerssaw Saturn

more clearly and made more discoveries about this mysteriousplanet.

More missions to Saturn should answer many questions astronomershave

about Saturn. But the discoveries they make may lead tomany more

questions. Saturn holds enough mysteries to keep astronomersbusy for

centuries to come.

The Study of Saturn

For hundreds of years, astronomers have been learning aboutSaturn

through telescopes. Because the telescopes were on Earth,air currents

and haze in the Earth's atmosphere always blurred theirimage of Saturn.

Then, in the mid-1970s, the National Aeronautics and Space

Administration (NASA) sent three spacecraft into space.They first flew

to Jupiter and then on to Saturn. The first to arrive atSaturn was

Pioneer 11. It was followed a few years later by Voyager1 and Voyager

2. They radioed pictures back to Earth.

The Sixth Planet

Saturn is the sixth planet from the sun. It orbits thesun at a

distance of 888 million miles. This is ten times fartheraway from

Earth. Saturn is a giant ball of gas. The gas is mostlyhydrogen and

helium, with very small amounts of methane and ethane mixedin. The

planet has no surface but astronomers believe it has arocky core.

The gas in Saturn's upper atmosphere is very cold. It isalmost 287

degrees below zero Fahrenheit. Strong winds blow aroundthe planet at

speeds of up to 1,110 miles per hour. Some clouds of Saturnare the same

color of butterscotch. Between the clouds are what looklike narrow

bands circling the planet parallel to its equator. Thereare also dark,

oval-shaped storms on the planet. But both the bands andovals are hard

to see because the highest part of Saturn's atmosphereis hazy.

Sometimes the weather on Saturn changes. A short time afterNASA's

Hubble Space Telescope was launched, astronomers noticedthat a huge

white cloud was beginning to form over Saturn's equator.The HST was

pointed toward the planet so that the cloud could be studied.For

several months, the cloud spread across the equator androse higher and

higher. Astronomers believe it to be made of ammonia icecrystals, but

they don't know what caused it to form.

Saturn's Moons

When the Voyager spacecraft approached Saturn, astronomersknew the

planet had ten moons. By the time the spacecraft passedby the planet,

seven new moons had been discovered. Today, the officialnumber moon

count is up to 18. But that number is likely to increasewith new space

missions to the planet. There are probably many small moonsorbiting

Saturn, waiting to be discovered.

Saturn's moons come in all shapes and sizes. Tiny potato-shapedAtlas is

19 miles long and 12 miles wide. It is the second closestof Saturn's

known natural satellites and orbits just 10,600 miles abovethe planet's

clouds. Atlas and several other of Saturn's smallest moonsare probably

fragments of smashed larger moons.

Farthest out, about 8 million miles away, is Phoebe. Phoebeis about the

size of the states New Hampshire and Vermont combined.This moon is very

strange. It orbits the planet in the opposite directionfrom all the

rest. Because of this, astronomers think that Phoebe isnot really one

of Saturn's natural moons. It is probably a stray asteroidthat was

captured into orbit by Saturn's gravitational pull.

One of Saturn's moons, Titan, is so large that it has itsown

atmosphere. Some astronomers think the atmosphere may besimilar to what

Earth's atmosphere was like billions of years ago. If Titan'satmosphere

is really like ancient Earth's atmosphere, then studyingTitan's

atmosphere would be like opening a history book of Earth.For this to

happen, a moon or a planet must have a strong gravitationalfield, to

keep the gas from escaping into space. Titan has a diameterof 3,200

miles. That's 200 miles bigger than the diameter of theplanet Mercury!

Astronomers are very interested in Titan because of itsunusual

atmosphere. It is made of nitrogen and methane gases. Thepressure of

the thick layer of gases at Titan's surface is equal towhat you would

experience if you were diving under Earth's oceans at adepth of 16

feet. Titan is very cold. Instruments on the spacecraftthat flew by

Titan measured the moon's surface temperature at 290 degreesbelow zero

Fahrenheit. Despite the cold, chemical reactions occurin its

atmosphere. These reactions form poisonous gases, suchas ethane. Some

of the gases become rain or snow that falls to the moon'ssurface. Some

astronomers think Titan may have lakes or oceans of liquid

methane-ethane, with islands of water ice.

Another of Saturn's interesting moons is Enceladus. Enceladusappears

to be made entirely of water ice, which gives this moona very bright

surface. The surface has cracks and valleys. This showsthat Enceladus

has a crust that moves as Earth's crust does.

Closer to Saturn than Enceladus is the moon Mimas. Witha diameter of

244 miles, Mimas is one of Saturn's smaller moons. Butin spite of its

small size, the moon is really remarkable. Mimas has acrater 81 miles

in diameter smashed into its surface! The center of thecrater has a

mountain more than 6 miles long jutting out into space.The mountain is

almost a mile higher than Mount Everest. Sometime in thepast, a large

object struck this moon. The impact blasted out a big craterand created

a lot of heat. The surface of Mimas melted in the heatand splashed out.

If you throw a stone in a pond of water, you can see whathappened next.

When the stone hits the water, it makes a hole. Water rushesback to

fill the hole and sloshes up the middle. The same thinghappened where

the meteor hit Mimas, but with one difference. Before themolten rock

could settle down, it froze in the middle and formed amountain.

Other strange moons orbit Saturn. Half of the moon Iapetusis dark in

color, and half is light. Iapetus is made mainly of ice.Scientists

think its dark side must have little impurities to giveit the darker

color.

Little Hyperion has taken a real beating. Its surface isfull of meteor

holes. Tethys has a giant valley system that stretchesover nearly three

fourths of its surface. The valley is many times largerthan the Grand

Canyon on earth.

I hope you enjoyed this tour of this spectacular planet.